Easy Ham and Cheese Appetizer Sandwiches

Ingredients (8)

• + 1 cup butter, softened add to pantry
• + 3 tablespoons poppy seeds add to pantry
• + 1 onion, grated add to pantry
• + 1 tablespoon Worcestershire sauce add to pantry
• + 2 tablespoons prepared Dijon-style mustard add to pantry
• + 2 (12 ounce) packages white party rolls add to pantry
• + ½ pound chopped cooked ham add to pantry
• ✓ 5 ounces shredded Swiss cheese